Significance A unique avian-origin H7N9 influenza virus caused 134 human infections with 44 deaths. The host factors contributing to moderate vs. severe disease are not clear. Here, we show that H7N9 severity was associated with a higher level of cytokines/chemokines. We demonstrate that the cytokines in the infected lung were 100- to 1,000-fold higher than those in the plasma. Furthermore, we found that the IFN-induced transmembrane protein-3 (IFITM3) C/C genotype was associated with severe clinical outcome, as reflected by reduced time in seeking medical aid; more rapid progression to acute respiratory distress syndrome; and higher viral load, cytokine/chemokine levels, and mortality rate. Overall, our data suggest that the IFITM3 genotype is a primary driver of the observed differences in clinical outcome after H7N9 infection.

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COVID-19 caused by a novel coronavirus SARS-CoV-2 emerged in Wuhan, Hubei province since December 2019, and caused a rapid outbreak throughout China and globally. Cities outside Hubei are also facing great challenge and require implementing of effective and feasible strategy in precision diagnosing novel coronavirus pneumonia (NCP).We described a multicenter prospective study on diagnostic strategy of suspected NCP patients from January 22 nd to February 9 th , 2020 in Eastern China cities. Nasopharyngeal swabs were collected from the patients. The epidemiological characteristics, clinical symptoms, laboratory assessments, and computed tomographic (CT) scans were obtained. Pathogen screen were performed including RT-PCR, multiplex PCR, rapid flu antigen tests and mNGS.We enrolled 53 suspected NCP patients, among whom 20 were laboratory-confirmed. Fourteen (70%) and 3 (15%) patients were positive for the first and second SARS-CoV-2 RT-PCR test, respectively. All NCP patients were positive for mNGS. Chest CT images and the symptoms of early stage NCP patients were similar to other viral pneumonia patients. We identified 11 of 20 co-infections in NCP cases, including regular respiratory virus, fungi and bacteria synchronously. Genomic analysis showed that 8 of 10 cases had no mutation in virus genome, while 2 cases had only one single mutation in N gene.Our study discovered that a combination of chest CT, SARS-CoV-2 RT-PCR and multi-plex PCR is recommended in regions outside Hubei province. Co-infection of other pathogens with SARS-CoV-2 exists and should be acknowledged. Repeated sampling, change of specimen type or metagenomics sequencing could further facilitate during critical clinical cases.

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